The present invention relates to the field of downhole oil, gas and/or geothermal exploration and more particularly to the field of percussive tools used in drilling. More specifically, the invention relates to the field of downhole jack hammers and vibrators which may be actuated by the drilling fluid or mud.
Percussive jack hammers are known in the art and may be placed at the end of a bottom hole assembly (BHA). There they act to more effectively apply drilling power to the formation, thus aiding penetration into the formation.
U.S. Pat. No. 7,424,922 to Hall, et al., which is herein incorporated by reference for all that it contains, discloses a jack element which is housed within a bore of a tool string and has a distal end extending beyond a working face of the tool string. A rotary valve is disposed within the bore of the tool string. The rotary valve has a first disc attached to a driving mechanism and a second disc axially aligned with and contacting the first disc along a flat surface. As the discs rotate relative to one another at least one port formed in the first disc aligns with another port in the second disc. Fluid passed through the ports is adapted to displace an element in mechanical communication with the jack element.
Percussive vibrators are also known in the art and may be placed anywhere along the length of the drill string. Such vibrators act to shake the drill string loose when it becomes stuck against the earthen formation or to help the drill string move along when it is laying substantially on its side in a nonvertical formation. Vibrators may also be used to compact a gravel packing or cement lining by vibration, or to fish a stuck drill string or other tubulars, such as production liners or casing strings, gravel pack screens, etc., from a bore hole.
U.S. Pat. No. 4,890,682 to Worrall, et al., which is herein incorporated by reference for all that it contains, discloses a jarring apparatus provided for vibrating a pipe string in a borehole. The apparatus thereto generates at a downhole location longitudinal vibrations in the pipe string in response to flow of fluid through the interior of said string.
U.S. Pat. No. 7,419,018 to Hall, et al., which is herein incorporated by reference for all that it contains, discloses a downhole drill string component which has a shaft being axially fixed at a first location to an inner surface of an opening in a tubular body. A mechanism is axially fixed to the inner surface of the opening at a second location and is in mechanical communication with the shaft. The mechanism is adapted to elastically change a length of the shaft and is in communication with a power source. When the mechanism is energized, the length is elastically changed.
Not withstanding the preceding patents regarding downhole jack hammers and vibrators, there remains a need in the art for more powerful mud actuated downhole tools. There is also a need in the art for means to easily adjust the force of the downhole tool. Thus, further advancements in the art are needed.